| Anaerobic digestion(AD)technology converts organic waste degradation into high value-added biogas through the anaerobic metabolism of microorganisms under anaerobic conditions.The current AD technology has drawbacks,such as low gas production rate,incomplete degradation of substrate,long digestion cycle,and low comprehensive utilization rate of digestate.In this regard,changing the digestion mode and adding accelerants can effectively solve these problems.Using dairy manure(DM)and acorn slag waste(ASW)as co-digestion substrates and adding biomass-derived carbon-based accelerants are expected to improve the comprehensive performance of the AD system.In this study,the anaerobic co-digestion of DM and ASW was first experimented.These two bio-wastes were mixed at different ratios,and the wet weight ratios were 1:0,3:1,1:1,1:3,and 0:1.Results indicated that when the ratio of ASW to DM was 1:3,the anaerobic co-digestion system obtained the best digestion performance and corresponding performance parameters.At this time,the cumulative biogas production of the digestion system reached 409.2 m L g-1 VS-1,the total solid(TS)removal rate was42.45%,the volatile solid(VS)removal rate was 53.29%,and the chemical oxygen demand(COD)degradation rate was 54.96%.In addition,the stability and fertility of the digestate obtained from the co-digestion system,compared with the single digestion system,were significantly improved.Given that the ratio of ASW to DM was 1:3,the effects of two biomass-derived carbon-based additives on the performance of the mesophilic anaerobic co-digestion system were further investigated using DM and ASW as co-substrates and sewage sludge as inoculum.Results showed that the biogas production,TS and VS removal rates,and COD degradation rate of the co-digestion system were significantly improved after the introduction of the two types of bio-based additives.A comprehensive investigation of the various indexes of the co-digestion system confirmed that the optimal addition amount of the two additives was 2.16 g/L.The co-digestion system with aloe peel-derived carbon additive reached the highest cumulative biogas production(580.9 m L g-1 VS-1),TS removal rate(55.70%),VS removal rate(67.68%),and COD degradation rate(79.37%),which were increased by 41.96%,31.21%,27.00%,and 44.41%,respectively,compared with the control group.Further investigation on the stability and fertility of digestate indicated that the digestate with biomass-derived carbon-based additive presented further remarkable stability and obtained a relatively low weight loss rate(46.65%-50.94%).Fertility test results showed that after introducing carbon-based additives,the digestate had suitable total nitrogen(3.07%-3.19%),phosphorus(1.16%-1.18%),and potassium(2.68%-2.79%)contents and relatively high total nutrient content(6.93%-7.14%).In general,DM and ASW are used as co-substrates for anaerobic co-digestion,and bio-wastes(aloe peel and acorn shell)are successfully prepared into biomass-derived porous carbon materials as additives to improve the performance of biogas production and digestate.Such performance of the digestion system fully realizes the comprehensive utilization of waste resources.This result proves that the combination of co-digestion mode and carbon-based additive can greatly enhance the digestion performance and operational stability of the AD system,and effectively improve the utilization of organic substrates and the availability of digestate.This work provides a strategy for further achieving resource recycling. |
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